In his Op-Ed in the New York Times this morning, Loading The Climate Dice, Nobel Prize winning economist Paul Krugman clearly defines the problem with telling the climate change story: It's about probabilities.

Krugman points to a new paper (pdf) by NASA scientist James Hansen and associates that answers the essential problem, "The greatest barrier to public recognition of human-made climate change is the natural variability of climate." Hansen, who first used the Goddard Institute for Space Studies three-dimensional model to forecast global climate changes in 1988, invented the term "climate dice' to explain how the levels of atmospheric carbon "load the dice," and make extreme weather more likely.

Because climate effects are most noticeable to the general public in the summer, the groups current report focuses on temperature anomalies in the summer months, comparing 1955, 1965 and 1975 to the last six years. Their conclusion is that there is no explanation other than global warming for a pattern "three standard deviations warmer than climatology':

"Climate dice", describing the chance of unusually warm or cool seasons relative to climatology, have become progressively "loaded" in the past 30 years, coincident with rapid global warming. The distribution of seasonal mean temperature anomalies has shifted toward higher temperatures and the range of anomalies has increased. An important change is the emergence of a category of summertime extremely hot outliers, more than three standard deviations (σ) warmer than climatology. This hot extreme, which covered much less than 1% of Earth's surface in the period of climatology, now typically covers about 10% of the land area. We conclude that extreme heat waves, such as that in Texas and Oklahoma in 2011 and Moscow in 2010, were "caused" by global warming, because their likelihood was negligible prior to the recent rapid global warming.

Although each hot summer raises public awareness that "the frequency of unusually warm seasons has increased," any fluctuation in that pattern allows climate change deniers to question the whole notion. I received a comment to my post yesterday about Bill McKibben's Rolling Stone article “Global Warming’s Terrifying New Math,” that said, "Before you invest another micro second with McKibben’s theories ask him to predict global temps for at least ten years. Twenty would better. Without some track record of successful prediction all of this anthropogenic global warming stuff is -pardon the expression -just so much hot gas."

How probable do the probabilities have to get before they cross the threshold of certainty in the public mind? Apparently still more certain. And this is not just about climate change, but about the difficulty of telling any complex story, or selling any complex product, to the wider public in a sound-bite, Facebook update, 140 character tweet world.

Although the technology of our world is shaped by probabilities, we still do not understand statistical correlation intuitively. When confronted with a probability we still collapse it into a cause—or not. The fact that the general public may think this summer's extreme weather is caused by global warming, means that they can question (or be compelled to question) the effect if next summer is cooler.

For people with any degree of comfort with information graphics, the charts in Hansen's paper are very convincing. But the American public is indeed uncomfortable with quantitative analysis of any kind that goes beyond a single level of causation. This year's extreme weather is not caused by global warming, it has been made much more likely by global warming. But that's a second degree of causation, a derivative effect.

The difficulty of telling the climate story is strikingly similar to that area of the economy that makes the most use of derivative effects, the finance industry. The question for Hansen, and Krugman and McKibben is not just how to convince the public "that human-made climate change is underway and will have unacceptable consequences if effective actions are not taken to slow the climate change," to quote Hansen's paper. The question is how to talk about complex quantitative things—the financial crisis, the climate crisis, the Higgs boson—in terms that a quantitatively challenged (and averse) public will intuitively understand.